Initial commit of responsive code for very small screen sizes
More tiny-size responsive code. Harmoizes the transition between super tiny and kinda tiny. Addes tagline back into hero unit at small sizes.
Adjusts breakpoint for small sizes after testing on slightly larger mobile-ish size. A larger screen will recieve the tiniest styles.
Merge pull request #200 from 18F/responsive-code-for-tiniest

Responsive code for tiniest size.